JP6879776B2 - Rotation control device - Google Patents

Description

The present invention relates to a rotation control device that controls the rotation of an operation target shaft, for example, an electric actuator that operates a valve shaft of a control valve.

Generally, the rotation control device that controls the rotation of the shaft to be operated detects the mechanical displacement of the shaft in the rotation direction by the position sensor, and determines the operation amount of the shaft based on the detection result. For example, in the electric operation device for operating the valve shaft of the rotary type regulating valve such as a ball valve (actuator), using a potentiometer consisting of a variable resistor as a position sensor, the rotational direction of the valve shaft detected by the potentiometer The valve shaft is controlled based on the amount of mechanical displacement of (see Patent Document 1).

Further, as a position sensor for measuring the amount of mechanical displacement in the rotation direction of the shaft, in addition to a contact type position sensor represented by a potentiometer, the absolute position in the rotation direction of the shaft to be measured is not contacted. There are known non-contact type absolute position sensors that detect with, and non-contact type relative position sensors that detect the relative position of the axis to be measured in the rotational direction in a non-contact manner. For example, as a non-contact type absolute position sensor, an absolute rotary encoder that outputs a code signal corresponding to the absolute angular position of the detection target axis is used, and as a non-contact type relative position sensor, a detection target. Incremental rotary encoders that output a pulse corresponding to the rotation angle of the shaft are known (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2011-74935 Japanese Unexamined Patent Publication No. 2010-286444

In general, a potentiometer is a sensor that outputs a change in resistance value by mechanically operating a slider, so that the durability tends to be low and the product life tends to be short. In addition, when an absolute rotary encoder as an absolute non-contact position sensor is used instead of the potentiometer, the unit cost of parts is generally high, and a separate battery for driving the absolute rotary encoder is required. Therefore, the product cost increases.

Therefore, the inventor of the present application has examined the use of a non-contact position sensor such as a rotary encoder in place of a potentiometer in an electric manipulator that operates a control valve. As a result of the examination, it became clear that there are the following problems.

When an incremental rotary encoder is used as a non-contact relative position sensor in an electric controller, the number of pulses output from the rotary encoder is counted from the measurement start point (origin), and the pulses are counted. It is necessary to calculate the absolute position of the valve shaft as the operation target shaft in the rotation direction based on the integrated value of the numbers. Therefore, immediately after the power is turned on, it is essential to return the valve shaft to the origin once and reset the integrated value of the number of output pulses of the rotary encoder by "returning to origin".

The "origin" in this return to origin is the position of the valve shaft at which the valve opening is fully closed (hereinafter, also referred to as "fully closed position") or the position of the valve shaft at which the valve opening is fully opened (hereinafter, "" When set to the "fully open position"), the electric actuator that operates the control valve has a problem that it takes a long time to complete the home return.

For example, an electric actuator for operating a control valve includes a reduction gear including an electric motor and a gear mechanism for reducing the rotational torque of the electric motor, and the output shaft is generated by the rotational torque decelerated by the reduction gear. By rotating, the valve shaft connected to the output shaft is operated.

Generally, in an electric actuator, the reduction ratio by this reduction gear is set to one hundredth to one thousandth, so that the time required for the valve shaft to move from the fully open position to the fully closed position is required. (Full stroke time) becomes too long to ignore. For example, in a conventional electric actuator, it takes about 60 seconds for the valve shaft to reach the fully open position to the fully closed position.

Therefore, if the conventional electric manipulator is provided with an incremental rotary encoder instead of the potentiometer and the origin of the valve shaft is set to the fully closed position, the valve shaft is returned to the origin from the fully open position. It will take at least 60 seconds to complete the home return. The same applies when the origin is set to the fully open position and the valve shaft is returned to the origin from the fully closed position.

In this way, in the electric control valve, when a non-contact relative position sensor is used instead of the potentiometer and the origin position in the origin return is set to the fully closed position or the fully open position, the origin return is completed. There is a problem that the waiting time until is long.

Further, when a non-contact relative position sensor is used, the valve opening degree of the control valve may not be controlled accurately. For example, when an electric actuator using an incremental rotary encoder is operated for a long time without returning to the origin, backlash generated in gears constituting a speed reducer or the like is accumulated when the rotation direction of the valve shaft is switched. However, an error occurs in the measurement result of the valve opening. Further, when an electric motor such as a stepping motor or a synchronous motor is used in an open loop, if the electric motor is stepped out, an error occurs in the measurement result of the valve opening degree. Further, in the synchronous motor, an error occurs in the measurement result of the valve opening due to the fluctuation of the power supply frequency or the like.

In this way, when a relative non-contact sensor is used instead of the potentiometer, the direction of rotation of the valve shaft by the relative non-contact sensor due to cumulative backlash, step-out of the open-loop electric motor, and fluctuation of the power supply frequency. There is a risk that the valve opening control of the control valve will not be performed accurately due to the large measurement error of the mechanical displacement amount.

The present invention has been made in view of the above problems, and an object of the present invention is an operation target in a rotation control device that measures a position in a rotation direction of an operation target axis by a non-contact relative position sensor. The purpose is to shorten the time required for the axis to return to the origin and to reduce the error in measuring the position of the axis to be operated.

The rotation control device (100) for controlling the rotation of the operation target shaft (200) according to the present invention includes a relative position sensor (1) that non-contactly detects the amount of mechanical displacement of the operation target shaft in the rotation direction. In the rotatable range (SR) from the first position (Pc) to the second position (Po) in the rotation direction of the operation target axis, it is provided corresponding to each of a plurality of different positions, and the operation target axis corresponds to the rotation range (SR). A plurality of absolute position sensors (2_1 to 2_n) that output detection signals when they reach a position, and an integrated value (RP) of mechanical displacement detected by the relative position sensor after the detection signal is output. ) And the position calculation unit (3) that calculates the absolute position in the rotation direction of the operation target axis based on the reference value (AP) indicating the position corresponding to the absolute position sensor that output the detection signal. , The operation amount (MV) of the operation target axis is calculated based on the information (SP) of the target position in the rotation direction of the operation target axis and the absolute position (PV) of the operation target axis calculated by the position calculation unit. Based on the operation amount calculation unit (4) to be calculated and the operation amount calculated by the operation amount calculation unit, the operation target axis is set within the rotatable range from the first position to the second position in the rotation direction of the operation target axis. It is provided with an operation unit (5) to be operated, and at least one of the plurality of absolute position sensors corresponds to a third position (Pa, Pm, Pb) excluding the first position and the second position in the rotatable range. It is characterized in that it is provided.

In the rotation control device, the position calculation unit may reset the integrated value of the mechanical displacement when the detection signal is output from the absolute position sensor.

In the rotation control device, the third position may be an intermediate point (Pm) between the first position and the second position.

In the rotation control device, even if one of the plurality of absolute position sensors outputs a detection signal when the operation target axis reaches the first position (position Pc where the valve opening becomes 0%). Good.

In the rotation control device, even if one of the plurality of absolute position sensors outputs a detection signal when the operation target axis reaches the second position (position Po where the valve opening becomes 100%). Good.

In the rotation control device, the operation target shaft is the valve shaft (200) of the control valve, and the first position is the position in the rotation direction of the valve shaft when the valve opening degree of the control valve becomes 0%. The second position is the position in the rotation direction of the valve shaft when the valve opening of the control valve is 100%, and the third position is the position when the control valve has a valve opening other than 0% and 100%. It may be the position of the valve shaft of.

In the rotation control device, the relative position sensor may be an incremental rotary encoder.

In the rotation control device, the absolute position sensor may be a limit switch.

In the above description, as an example, reference numerals on the drawings corresponding to the components of the invention are described in parentheses.

As described above, according to the present invention, in the rotation control device that measures the position of the operation target axis in the rotation direction by the non-contact relative position sensor, the time required for returning the operation target axis to the origin is shortened. Moreover, it is possible to reduce the error of the position measurement of the operation target axis.

FIG. 1 is a diagram showing a configuration of a rotation control device according to the first embodiment. FIG. 2 is a diagram showing an arrangement example of the absolute position sensor. FIG. 3A is a diagram showing an example of a specific structure of the absolute position sensor. FIG. 3B is a diagram showing an example of a specific structure of the absolute position sensor. FIG. 3C is a diagram showing an example of a specific structure of the absolute position sensor. FIG. 3D is a diagram showing an example of a specific structure of the absolute position sensor. FIG. 3E is a diagram showing an example of a specific structure of the absolute position sensor. FIG. 4 is a diagram showing an operation flow in the origin return operation mode of the rotation control device according to the first embodiment. FIG. 5 is a flow chart showing an operation flow in the normal operation mode of the rotation control device according to the first embodiment. FIG. 6 is a diagram showing another arrangement example of the absolute position sensor. FIG. 7 is a diagram showing another arrangement example of the absolute position sensor. FIG. 8 is a diagram showing an example of another specific structure of the absolute position sensor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals will be given to the components common to each embodiment, and the repeated description will be omitted.

<Embodiment 1>
<< Configuration of rotation control device >>
FIG. 1 is a diagram showing a configuration of a rotation control device according to the first embodiment.
The rotation control device 100 shown in the figure is, for example, an electric actuator that controls the rotation of the valve shaft of a rotary type control valve such as a ball valve used for process control of a flow rate in a plant or the like.

Specifically, the rotation control device 100 includes a target value (set value) SP of the valve opening of the control valve given by a higher-level device (not shown) and an actually measured value of the valve opening of the control valve (hereinafter, "actual opening"). It is also referred to as "degree".) An operator that calculates the deviation ΔP from PV and drives the valve shaft 200 so that the deviation ΔP becomes 0, thereby controlling the valve opening degree of the control valve to be the target value. Is.

Hereinafter, a specific configuration of the rotation control device 100 will be described.
As shown in FIG. 1, the rotation control device 100 includes a relative position sensor 1, a plurality of absolute position sensors 2_1 to 2_n (n is an integer of 2 or more), a position calculation unit 3, an operation amount calculation unit 4, and an operation amount calculation unit 4. The operation unit 5 is provided.

These functional parts are housed inside a housing made of, for example, a metal material. In addition to the above-mentioned functional unit, the rotation control device 100 transmits / receives data to / from a display unit (for example, a liquid crystal display) for presenting various information such as the valve opening degree of the control valve to the user and an external device. A communication circuit or the like for performing the above may be provided.

First, the relative position sensor 1 and the absolute position sensors 2_1 to 2_n for measuring the actual opening degree of the control valve, that is, the position of the valve shaft 200 in the rotational direction will be described.

The relative position sensor 1 is a functional unit that non-contactly detects the mechanical displacement of the valve shaft 200 as the operation target shaft of the rotation control device 100 in the rotation direction. As the relative position sensor 1, an incremental rotary encoder that outputs a pulse corresponding to the rotation angle of the detection target axis (valve shaft 200) can be exemplified. In the present embodiment, the relative position sensor 1 will be described as an incremental rotary encoder.

The absolute position sensors 2_1 to 2_n are functional units that output a detection signal when the valve shaft 200, which is the operation target shaft, reaches a predetermined position in the rotation direction. The absolute position sensors 2_1 to 2_n may be any component capable of outputting an electric signal indicating that the valve shaft 200 has reached a specific position in the rotation direction. Specifically, as the absolute position sensor 2_1 to 2_n, for example, a limit switch, a photo interrupter, a Hall element, or the like can be used. Here, the electric signal may be any signal indicating that the valve shaft 200 has reached a specific position in the rotation direction, and is, for example, an on / off signal (a signal indicating a state, for example, a digital signal).

FIG. 2 is a diagram showing an arrangement example of the absolute position sensors 2_1 to 2_n. The figure shows an arrangement example of the absolute position sensors 2_1 to 2_5 when n = 5.

As shown in FIG. 2, the absolute position sensors 2_1 to 2_5 are provided corresponding to a plurality of different positions within the rotatable range SR of the valve shaft 200, and the valve shaft 200 reaches the corresponding position. When this is done, the detection signal is output respectively.

Here, the rotatable range SR is a movable range of the valve shaft 200 in the rotation direction. For example, from the fully closed position Pc where the valve opening degree as the first position is 0%, the valve as the second position. The range up to the fully open position Po where the opening degree is 100% is shown.

In the rotation control device 100, the absolute position sensors 2_1 to 2_5 are provided corresponding to any position in the range where the valve opening degree is from 0% to 100%. For example, in the case of the arrangement example shown in FIG. 2, the absolute position sensor 2_1 is provided corresponding to the fully closed position Pc in which the valve opening degree is 0%, and the absolute position sensor 2_2 has a valve opening degree of 20%. The absolute position sensor 2_3 is provided corresponding to the position Pa corresponding to the position Pa, and the absolute position sensor 2_3 is provided corresponding to the position Pm at which the valve opening degree is 50%. The absolute position sensor 2_5 is provided corresponding to the position Pb, and is provided corresponding to the fully open position Po at which the valve opening degree is 100%.

In the case of the arrangement example shown in FIG. 2, the absolute position sensor 2_1 outputs a detection signal when the valve shaft 200 reaches the fully closed position Pc. The absolute position sensor 2_2 outputs a detection signal when the valve shaft 200 reaches the position Pa (valve opening: 20%). The absolute position sensor 2_3 outputs a detection signal when the valve shaft 200 reaches the position Pm (valve opening: 50%). The absolute position sensor 2_4 outputs a detection signal when the valve shaft 200 reaches the position Pb (valve opening: 70%). The absolute position sensor 2_5 outputs a detection signal when the valve shaft 200 reaches the fully open position Po (valve opening: 100%).

Next, the specific structure of the absolute position sensors 2_1 to 2_n will be described.
3A to 3E are diagrams showing an example of a specific structure of the absolute position sensors 2_1 to 2_n. Here, the case where n = 5 is illustrated.

Specifically, FIG. 3A is a plan view schematically showing the structure of the absolute position sensor 2_1 to 2_n when the valve shaft 200 reaches one of the absolute position sensors 2_1 to 2_n, and FIG. 3B is a plan view schematically showing the structure of the absolute position sensor 2_1 to 2_n. It is a side view which shows typically the structure of the absolute position sensor 2_1-2_n when the valve shaft 200 reaches one of the absolute position sensors 2_1-2_n. Further, FIG. 3C is a plan view schematically showing the structure of the absolute position sensor 2_1 to 2_n when the valve shaft 200 does not reach any of the absolute position sensors 2_1 to 2_n, and FIG. 3D is a plan view schematically showing the structure of the absolute position sensor 2_1 to 2_n. It is a side view which shows typically the structure of the absolute position sensor 2_1-2_n when the valve shaft 200 does not reach any of the absolute position sensors 2_1-2_n. Further, FIG. 3E is another side view schematically showing the structure of the absolute position sensors 2_1 to 2_n.

The absolute position sensor 2_i (1 ≦ i ≦ n) can be realized by arranging the resistor R and the two electrodes 21 and 22 on the printed circuit board 20, for example, as shown in FIGS. 3A to 3E.

Specifically, the electrode 21 is formed on one main surface 20a of the printed circuit board 20, and the resistor R is connected between the electrode 21 and the power supply line Vcc to which the power supply voltage is supplied. Further, the electrode 22 is formed on the other main surface 20b of the printed circuit board 20, and the electrode 22 is connected to the ground line GND to which the ground voltage is supplied. Here, the resistor R may be arranged, for example, on one main surface 20a of the printed circuit board 20. Further, the power supply line Vcc may be formed on, for example, one main surface 20a of the printed circuit board 20, and the ground line GND may be formed on, for example, the other main surface 20b of the printed circuit board 20.

On the main surface 20a of the printed circuit board 20, an IC chip 30 including a program processing device such as a microprocessor and a CPU that functions as a position calculation unit 3 and an operation amount calculation unit 4 described later is arranged. Here, the node na to which the above-mentioned resistor R and the electrode 21 are connected is connected to any one input terminal of the IC chip 30.

A through hole 20c that penetrates the main surfaces 20a and 20b is formed in the printed circuit board 20, and a valve shaft 200 is inserted through the through hole 20c. A short plate 201 made of metal is joined to the outer peripheral surface of the valve shaft 200.

As shown in FIGS. 3B and 3D, the short plate 201 is formed, for example, in a U-shape in front view. The short plate 201 is fixed to the valve shaft 200 with a pair of opposite end portions 201a and 201b sandwiching the printed circuit board 20, and rotates together with the valve shaft 200.

As shown in FIG. 3A, for example, when the valve shaft 200 rotates and the short plate 201 reaches the position of the absolute position sensor 2_3, the end portion 201a of the short plate 201 comes into contact with the electrode 21 of the absolute position sensor 2_3. At the same time, the end portion 201b of the short plate 201 comes into contact with the electrode 22 of the absolute position sensor 2_3. At this time, a current path is formed from the power supply line Vcc to the ground line GND via the resistor R, the electrode 21, the short plate 201, and the electrode 22, and the potential of the node na becomes 0V (ground potential).

On the other hand, as shown in FIG. 3C , when the valve shaft 200 rotates and the short plate 201 reaches between the absolute position sensor 2_1 and the absolute position sensor 2_2, the ends 201a and 201b of the short plate 201 are set. It is in a state where it does not come into contact with the electrodes 21 and 22 of any of the absolute position sensors 2_1 to 2_5. As a result, the potential of the node na of each absolute position sensor 2_1 to 2_5 becomes Vcc (power supply voltage).

In this way, by inputting the voltage change of the node na of each absolute position sensor 2_1 to 2_5 into the IC chip 30 as a detection signal, it is possible to detect that the valve shaft 200 has reached a predetermined position in the rotation direction. It will be possible.

Next, the position calculation unit 3, the operation amount calculation unit 4, and the operation unit 5 will be described.

The position calculation unit 3 is a functional unit that calculates the absolute position of the valve shaft 200. The position calculation unit 3 outputs the integrated value of the mechanical displacement detected by the relative position sensor 1 after the detection signal of the absolute position sensor 2_1 to 2_n is output, and the absolute position sensor that outputs the detection signal. The absolute position in the rotation direction of the operation target axis is calculated based on the reference value indicating the position corresponding to 2_1 to 2_n.

The position calculation unit 3 can be realized by, for example, program processing by a program processing device such as a microcontroller or a CPU. In the case of the above example, it is realized by the IC chip 30 mounted on the printed circuit board 20.

More specifically, the position calculation unit 3 includes a reference value update unit 32, a relative position information acquisition unit 31, and a position determination unit 33.

The reference value updating unit 32 is a functional unit that updates the reference value AP and outputs the reset signal RST when the detection signal is output from the absolute position sensors 2_1 to 2_n.

Here, the reference value AP is a value indicating an absolute position within the rotatable range SR, and serves as a reference when calculating the absolute position of the valve shaft 200 in the rotation direction.

Specifically, the reference value updating unit 32 sets the reference value AP to the position corresponding to the absolute position sensor 2_1 to 2_n that outputs the detection signal each time the absolute position sensor 2_1 to 2_n outputs a detection signal. Set to the indicated value. For example, in the case of the example of FIG. 2, when the valve shaft 200 first rotates to reach the position Pa where the valve opening degree becomes 20% and the absolute position sensor 2_2 outputs a detection signal, the reference value update unit 32 Sets the reference value AP to a value indicating the position Pa corresponding to the absolute position sensor 2_2. After that, when the valve shaft 200 further rotates and the valve shaft 200 reaches the position Pm where the valve opening degree becomes 50% and the absolute position sensor 2_3 outputs a detection signal, the reference value update unit 32 sets the reference value. The AP is changed from the value indicating the position Pa to the value indicating the position Pm corresponding to the absolute position sensor 2_3.

The relative position information acquisition unit 31 is a functional unit that acquires the amount of mechanical displacement of the valve shaft 200 in the rotational direction detected by the relative position sensor 1 and calculates the integrated value RP of the amount of mechanical displacement. For example, the relative position information acquisition unit 31 counts the pulses output from the incremental rotary encoder as the relative position sensor 1 and calculates the integrated value RP of the number of pulses.

Further, when the reset signal RST is output from the reference value updating unit 32, the relative position information acquisition unit 31 resets the integrated value RP of the number of pulses counted up to that point. After the reset, the relative position information acquisition unit 31 resumes the pulse counting operation.

That is, the relative position information acquisition unit 31 resets the integrated value RP each time a detection signal is output from the absolute position sensors 2_1 to 2_n. Therefore, the integrated value RP calculated by the relative position information acquisition unit 31 is the accumulation of the number of pulses output from the rotary encoder from the time when the reference value AP is updated immediately before to the time when the reference value AP is updated next time. It becomes a value.

The position determination unit 33 is a mechanical displacement amount in the rotation direction of the valve shaft 200 based on the reference value AP generated by the reference value update unit 32 and the integrated value RP of the number of pulses calculated by the relative position information acquisition unit 31. And are added to calculate the absolute position of the valve shaft 200 in the rotatable range SR. The position determining unit 33 converts the calculated absolute position of the valve shaft 200 into a valve opening degree, and outputs the converted value as an actual opening degree PV.

The operation amount calculation unit 4 operates the valve shaft 200 based on the target value SP of the valve opening as the target position in the rotation direction of the valve shaft 200 and the actual opening PV calculated by the position calculation unit 3. It is a functional part that calculates. The operation amount calculation unit 4 can be realized by program processing by a program processing device such as a microcontroller or a CPU, as in the position calculation unit 3, for example. In the case of the above example, it is realized by the IC chip 30 mounted on the printed circuit board 20.

Specifically, the operation amount calculation unit 4 includes a target value acquisition unit 41, a deviation calculation unit 42, and an operation amount determination unit 43.

The target value acquisition unit 41 is a functional unit that acquires the target value SP of the valve opening degree given by, for example, a higher-level device (not shown) in the valve control system. The target value SP is set by communication from an external controller or an analog signal of, for example, 4-20 mA.

The deviation calculation unit 42 is a functional unit that calculates the deviation ΔP between the target value SP of the valve opening degree acquired by the target value acquisition unit 41 and the actual opening degree PV calculated by the position calculation unit 3.

The operation amount determination unit 43 calculates the operation amount MV required for the valve shaft 200 to reach the target position in the rotation direction based on the target value SP based on the deviation ΔP calculated by the deviation calculation unit 42.

The operation unit 5 is a functional unit that operates the valve shaft 200 within the rotatable range SR based on the operation amount MV calculated by the operation amount calculation unit 4. Specifically, the operation unit 5 includes an electric motor 52, an electric motor drive unit 51, and a speed reducer 53.

The electric motor 52 is a component that generates a rotational force for operating the valve shaft 200. Examples of the electric motor 52 include brushless motors, stepping motors, and synchronous motors.

The electric motor drive unit 51 is a functional unit that drives the electric motor 52. Specifically, the electric motor drive unit 51 rotates the output shaft of the electric motor 52 by applying a current (or voltage) corresponding to the operation amount MV calculated by the operation amount calculation unit 4 to the electric motor 52. ..

The speed reducer 53 is a power transmission mechanism that reduces the rotational force generated by the electric motor 52 and transmits it to the valve shaft 200. For example, the speed reducer 53 is composed of various gear mechanisms such as a planetary gear mechanism. By connecting the output shaft of the speed reducer 53 to the valve shaft 200, the valve shaft 200 can be rotated by the rotational force obtained by reducing the rotational force of the electric motor 52 by a predetermined reduction ratio.

<< Operating Principle of Rotation Control Device 100 According to Embodiment 1 >>
Next, the operating principle of the rotation control device 100 according to the first embodiment will be described.
First, the operation of returning to the origin by the rotation control device 100 will be described.

FIG. 4 is a diagram showing an operation flow in the origin return operation mode of the rotation control device 100 according to the first embodiment.
Here, a case where the valve shaft 200 has reached a position where the valve opening degree becomes 80% at the time of turning on the power of the rotation control device 100 will be described as an example.

When the power is turned on to the rotation control device 100, the rotation control device 100 starts the operation in the origin return operation mode in which the origin return process of the relative position sensor is performed. In the home-return operation mode, the rotation control device 100 drives the electric motor 52 in the direction of closing the control valve (S11). Specifically, the electric motor drive unit 51 drives the electric motor 52 based on the operation amount MV calculated by the operation amount determination unit 43 so that the valve opening degree becomes 0%.

Next, the rotation control device 100 determines whether or not the detection signal is output from the absolute position sensors 2_1 to 2_n (S12). If the detection signal is not output from the absolute position sensors 2_1 to 2_n in step S12, the rotation control device 100 continues to drive the electric motor 52 so that the valve opening degree becomes 0%.

On the other hand, when the detection signal is output from the absolute position sensors 2_1 to 2_n in step S12, the rotation control device 100 sets the valve shaft at the position corresponding to the absolute position sensors 2_1 to 2_n that output the detection signal. Let it be the reference value AP (initial point) when calculating the absolute position of 200 (S13).

For example, in the case of the example of FIG. 2, the valve shaft 200 rotates in the direction from the position where the valve opening is 80% to 0% in step S11, and then the valve shaft is moved to the position Pb where the valve opening is 70%. When 200 is reached, a detection signal is output from the absolute position sensor 2_4. At this time, the reference value updating unit 32 in the position calculation unit 3 sets a value indicating the position Pb corresponding to the absolute position sensor 2_4 that has output the detection signal as the reference value AP, and outputs the reset signal RST.

The relative position information acquisition unit 31 that has received the reset signal RST from the reference value update unit 32 resets the integrated value RP of the number of pulses counted up to that point (S14).

As a result, the home-returning process is completed, and the rotation control device 100 shifts from the home-returning operation mode to the normal operation mode.

Next, the operation of the rotation control device 100 in the normal operation mode after returning to the origin will be described.
FIG. 5 is a flow chart showing an operation flow in the normal operation mode of the rotation control device according to the first embodiment.

When the home position return operation mode ends, the rotation control device 100 shifts to the normal operation mode. In the normal operation mode, the rotation control device 100 waits until the host device instructs to change the target value SP of the valve opening degree (S20). When a change in the target value SP of the valve opening is instructed, the deviation calculation unit 42 of the rotation control device 100 determines the actual opening PV based on the absolute position of the valve shaft 200 calculated by the position calculation unit 3. Is larger than the target value SP instructed by the host device (S21).

In step S21, when the actual opening PV is larger than the target value SP, the rotation control device 100 drives the electric motor 52 in the direction of closing the control valve (S22). Specifically, the operation amount determination unit 43 calculates the operation amount MV so that the valve opening becomes the target value SP based on the deviation ΔP calculated by the deviation calculation unit 42, and the electric motor drive unit 51 determines the operation amount MV. , The electric motor 52 is driven based on the operation amount MV.

On the other hand, in step S21, when the actual opening PV is smaller than the target value SP, the rotation control device 100 drives the electric motor 52 in the direction of opening the control valve (S23). Specifically, the operation amount determination unit 43 calculates the operation amount MV so that the valve opening becomes the target value SP based on the deviation ΔP calculated by the deviation calculation unit 42, and the electric motor drive unit 51 determines the operation amount MV. , The electric motor 52 is driven based on the operation amount MV.

After step S22 or step S23, the rotation control device 100 determines whether or not a detection signal is output from the absolute position sensors 2_1 to 2_n (S24).

In step S24, when the detection signal is not output from the absolute position sensors 2_1 to 2_n, the rotation control device 100 acquires the relative position information with the reference value AP set by the reference value update unit 32 immediately before. The actual opening PV (absolute position of the valve shaft 200) is determined based on the mechanical displacement of the valve shaft 200 based on the integrated value RP of the number of output pulses from the relative position sensor 1 calculated by the unit 31. Calculate (S27).

For example, if the detection signal has never been output from the absolute position sensors 2_1 to 2_n after the home return processing (steps S11 to S14) described above, the reference value set in step S13 of the home return operation mode By adding the amount of mechanical displacement of the valve shaft 200 based on the integrated value RP calculated by the relative position information acquisition unit 31 to the AP (the position where the valve opening is 70% in the above example), the actual displacement is achieved. Calculate the opening PV.

On the other hand, in step S24, when the detection signal is output from the absolute position sensors 2_1 to 2_n, the rotation control device 100 updates the reference value AP (S25). Specifically, the reference value updating unit 32 sets a position corresponding to the absolute position sensors 2_1 to 2_n that output the detection signal in the new reference value AP. For example, in the above-mentioned home position return operation mode, when a detection signal is output from the absolute position sensor 2_3 in step S24 immediately after the reference value AP is set to a value indicating the position Pb (valve opening: 70%). The reference value updating unit 32 changes the reference value AP from a value indicating the position Pb (valve opening: 70%) to a value indicating the position Pm (valve opening: 50%). At this time, the reference value updating unit 32 also outputs the reset signal RST.

The relative position information acquisition unit 31 that has received the reset signal RST from the reference value update unit 32 resets the integrated value RP of the number of output pulses of the relative position sensor 1 that has been counted up to that point (S26).

Next, the rotation control device 100 is based on the reference value AP set by the reference value update unit 32 in step S25 and the integrated value RP counted by the relative position information acquisition unit 31 after being reset in step S26. Then, the actual opening PV (absolute position of the valve shaft 200) is calculated (S27). For example, in step S25, when the reference value AP is changed to a value indicating the position Pm (valve opening: 50%), the reference value AP is counted by the relative position information acquisition unit 31 after step S26. The absolute position of the valve shaft 200 is calculated by adding the mechanical displacement amount of the valve shaft 200 based on the integrated value RP, and the actual opening PV is calculated from that position.

Next, the rotation control device 100 determines whether or not the actual opening PV calculated in step S27 matches the target value SP (S28).

If the actual opening PV does not match the target value SP in step S28, the process returns to step S21, and the rotation control device 100 again performs the above-mentioned processes (S21 to S27). On the other hand, in step S28, when the actual opening PV matches the target value SP, the rotation control device 100 ends a series of processes for setting the valve opening to the target value.

<< Effect of Rotation Control Device 100 According to Embodiment 1 >>
As described above, in the rotation control device 100 according to the present invention, in addition to the non-contact relative position sensor 1 as a position sensor for measuring the position of the valve shaft 200 in the rotation direction, the valve shaft 200 is fully closed. It is provided with absolute position sensors 2_2 to 2_4 that output a detection signal when the third position (Pa, Pm, Pb) excluding the position Pc and the fully open position Po is reached. The rotation control device 100 includes a reference value AP indicating a position corresponding to the absolute position sensor 2_2 to 2_4 that outputs the detection signal, and a mechanical detection by the relative position sensor 1 after the detection signal is output. The absolute position of the valve shaft 200 in the rotation direction is calculated based on the integrated displacement value RP.

According to this, not only the fully closed position Pc and the fully open position Po but also the third position can be regarded as a reference point in the position measurement of the valve shaft 200, that is, the “origin”, so that the fully closed position Pc or the fully open position is fully opened. Compared with the case where only the position Po is set as the origin, it is possible to shorten the time required for the process of returning to the origin.

Specifically, when n absolute position sensors 2_1 to 2_n are arranged within the rotatable range SR, it is necessary to return the valve shaft 200 at the fully open position Po to the origin when the rotation control device 100 is turned on. The time T is represented by the following equation (1). Here, Tf is the time (full stroke time) required for the valve shaft to move from the fully open position to the fully closed position.

For example, when five (n = 5) absolute position sensors 2_1 to 2_5 are arranged and the full stroke time Tf is 60 [seconds], the time required to return the valve shaft 200 at the fully open position Po to the origin. T is 60 / (5-1) = 15 [seconds].

As described above, according to the rotation control device 100 according to the present invention, the time required for returning to the origin of the valve shaft 200, which is required when the relative position sensor 1 such as the incremental rotary encoder is used, is shortened. Is possible.

Further, the rotation control device 100 according to the present invention performs the same process as the home return every time the valve shaft 200 passes through the third position excluding the fully closed position Pc and the fully open position Po. Specifically, when n = 5, the rotation control device 100 sets the reference value AP as the reference value AP when the detection signal is output from the absolute position sensors 2_2 to 2___, and the absolute position sensor that outputs the detection signal. The integrated value RP is reset while updating to the value indicating the position corresponding to 2_2 to 2_4.

According to this, even when the rotation control device 100 is operated for a long time, the cumulative back crash of the gears constituting the speed reducer 53 and the like described above, and the electric motor such as a stepping motor and a synchronous motor as the electric motor 52 Reduces the measurement error of the mechanical displacement of the valve shaft 200 by the relative position sensor 1 due to the step-out of the electric motor when using the open loop and the fluctuation of the power supply frequency when using the synchronous motor. can do. This makes it possible to control the valve opening degree of the control valve more accurately.

Further, according to the rotation control device 100, by providing a plurality of absolute position sensors 2_1 to 2_n, even if one of the absolute position sensors 2_1 to 2_n fails, the other absolute position sensors 2_1 to 2_n The valve opening control can be continued. Thereby, the reliability of the rotation control device 100 can be improved.

Further, by increasing the number of absolute position sensors 2_1 to 2_n installed in the rotatable range SR, the time required for returning to the origin and the measurement error of the mechanical displacement amount of the valve shaft 200 by the relative position sensor 1 can be further reduced. It becomes possible to do.

<Expansion of embodiment>
The inventions made by the present inventors have been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited thereto and can be variously modified without departing from the gist thereof. No.

For example, in the above embodiment, the case where five absolute position sensors 2_1 to 2_5 are installed is shown, but the number of absolute position sensors to be installed is not limited to this. Hereinafter, another example of arrangement of the absolute position sensor will be shown.

FIG. 6 is a diagram showing another arrangement example of the absolute position sensor.
In the figure, n = 3, the absolute position sensor 2_1 is placed at the fully closed position Pc where the valve opening is 0%, and the midpoint between the fully closed position Pc and the fully open position Po, that is, the valve opening is 50. The case where the absolute position sensor 2_2 is arranged at the position Pm which is% and the absolute position sensor 2_3 is arranged at the fully open position Po where the valve opening degree is 100% is shown.

According to this, when the valve shaft 200 reaches the fully closed position Pc, the fully open position Po, and the position Pm at the midpoint between the fully closed position Pc and the fully open position Po, the origin return (update of the reference value AP) is performed. Since this is performed, the time required to return to the origin and the measurement error of the mechanical displacement amount by the relative position sensor 1 should be reduced as compared with the case where only the fully closed position Pc or the fully open position Po is set as the origin of the valve shaft 200. Is possible. In addition, it is possible to reduce the additional cost of installing the absolute position sensor.

In FIG. 6, the absolute position sensor may be arranged in either of the fully closed position Pc in which the valve opening is 0% and the fully open position Po in which the valve opening is 100%. ..

FIG. 7 is a diagram showing still another example of arrangement of the absolute position sensor.
The figure shows a case where one absolute position sensor 2 is provided at a position Pm where the valve opening degree is 50%.

According to this, since the origin return is performed at the position Pm which is the intermediate point between the fully closed position Pc and the fully open position Po, the origin return is performed as compared with the case where only the fully closed position Pc or the fully open position Po is set as the origin. It is possible to reduce the time required for the measurement and the measurement error of the mechanical displacement amount by the relative position sensor 1. Further, since only one absolute position sensor is required, it is possible to further reduce the additional cost due to the installation of the absolute position sensor.

Further, in the above embodiment, the case where an incremental rotary encoder is used as the relative position sensor 1 is illustrated, but if it is possible to detect the mechanical displacement of the operation target axis in the rotational direction without contact. , Can be used as the relative position sensor 1. For example, when a brushless motor is used as the electric motor 52, the signal output from the Hall element (Hall IC) constituting the brushless motor can be used as the relative position sensor 1.

Further, when a stepping motor is used as the electric motor 52, the position calculation unit 3 counts the pulse signal for driving the stepping motor without separately providing the relative position sensor 1, so that the operation target axis can be operated. It is also possible to calculate the amount of mechanical displacement in the direction of rotation.

Further, when a synchronous motor is used as the electric motor 52, it is possible to calculate the amount of mechanical displacement of the operation target shaft in the rotation direction without separately providing the relative position sensor 1. For example, when the drive time for driving the synchronous motor is T [s], the rotation speed is N [rpm], and the reduction ratio of the reduction gear is 1 / G, the rotation angle Φ [°] is (T × N). It is represented by × 360) / (60 × G). Therefore, the position calculation unit 3 can calculate the amount of mechanical displacement of the operation target shaft in the rotation direction by performing the above calculation.

Further, in the above embodiment, the case where the rotation control device 100 is applied as an electric operator for operating the valve shaft 200 of the control valve is illustrated, but the operation target shaft operated by the rotation control device 100 is a valve. It is not limited to the axis, and can be applied to any opening measurement system that uses a relative position sensor in the rotation control device. For example, the rotation control device 100 can be applied as an actuator for a damper that operates the damper shaft.

Further, in the above embodiment, the case where the valve shaft 200 is inserted into the through hole 20c formed inside the printed circuit board 20 has been illustrated, but the present invention is not limited to this. For example, as shown in FIG. 8, for example, a semicircular notch 20d in a plan view may be provided on one side of the printed circuit board 20, and the valve shaft 200 may be arranged in the notch 20d. In this case, the electrodes 21 may be arranged around the notched portion 20d on the main surface 20a of the printed circuit board 20.

100 ... Rotation control device (operator), 200 ... Valve shaft, 1 ... Relative position sensor, 2,2_1 to 2_n ... Absolute position sensor, 3 ... Position calculation unit, 4,4A ... Operation amount calculation unit, 5 ... Operation unit, 31 ... Relative position information acquisition unit, 32 ... Reference value update unit, 33 ... Position determination unit, 41 ... Target value acquisition unit, 42 ... Deviation calculation unit, 43 ... Operation amount determination unit, 51 ... Electric motor drive Part, 52 ... Electric motor, 53 ... Reducer, SP ... Target value, PV ... Actual opening, ΔP ... Deviation, MV ... Operation amount, RP ... Integrated value, AP ... Reference value, RST ... Reset signal.

Claims (8)

A rotation control device that controls the rotation of the axis to be operated.
A relative position sensor that non-contactly detects the mechanical displacement of the axis to be operated in the rotational direction,
In the rotatable range from the first position to the second position in the rotation direction of the operation target axis, it is provided corresponding to each of a plurality of different positions, and is detected when the operation target axis reaches the corresponding position. Multiple absolute position sensors that output signals respectively,
The integrated value of the mechanical displacement detected by the relative position sensor after the detection signal is output and the reference value indicating the position corresponding to the absolute position sensor that outputs the detection signal. Based on the position calculation unit that calculates the absolute position of the operation target axis in the rotation direction,
The operation amount calculation unit that calculates the operation amount of the operation target axis based on the information of the target position in the rotation direction of the operation target axis and the absolute position of the operation target axis calculated by the position calculation unit. When,
Based on the operation amount calculated by the operation amount calculation unit, the operation unit that operates the operation target shaft within the rotatable range from the first position to the second position in the rotation direction of the operation target shaft. Prepare,
Each of the plurality of absolute position sensors
A first electrode formed on one surface of a printed circuit board arranged in the vicinity of the operation target axis and connected to a power supply line via a resistance element, and a first electrode.
A second electrode formed on the other surface of the printed circuit board and having a GND potential,
It includes a short plate joined to the outer peripheral surface of the operation target shaft and configured to short-circuit the first electrode and the second electrode when the operation target shaft is in a predetermined position.
The short plate is configured to output the voltage change generated in the first electrode as the detection signal to the position calculation unit when the first electrode and the second electrode are short-circuited.
At least one of the plurality of absolute position sensors is a rotation control device provided corresponding to the first position and the third position excluding the second position in the rotatable range. In the rotation control device according to claim 1,
The position calculation unit is a rotation control device characterized in that when the detection signal is output from the absolute position sensor, the integrated value of the mechanical displacement is reset. In the rotation control device according to claim 1 or 2.
The rotation control device, wherein the third position is an intermediate point between the first position and the second position. In the rotation control device according to any one of claims 1 to 3.
One of the plurality of absolute position sensors is a rotation control device that outputs the detection signal when the operation target axis reaches the first position. In the rotation control device according to any one of claims 1 to 3.
One of the plurality of absolute position sensors is a rotation control device that outputs the detection signal when the operation target axis reaches the second position. In the rotation control device according to any one of claims 1 to 5.
The operation target shaft is the valve shaft of the control valve.
The first position is a position in the rotation direction of the valve shaft when the valve opening degree of the control valve becomes 0%.
The second position is a position in the rotation direction of the valve shaft when the valve opening degree of the control valve is 100%.
The rotation control device is characterized in that the third position is the position of the valve shaft when the control valve has a valve opening degree other than 0% and 100%. In the rotation control device according to any one of claims 1 to 6.
The relative position sensor is a rotation control device characterized by being an incremental rotary encoder. A rotation control device that controls the rotation of the axis to be operated.
A relative position sensor that non-contactly detects the mechanical displacement of the axis to be operated in the rotational direction,
In the rotatable range from the first position to the second position in the rotation direction of the operation target axis, when the operation target axis reaches the third position excluding the first position and the second position, the detection signal is transmitted. Absolute position sensor to output and
An integrated value of the mechanical displacement detected by the relative position sensor from the time when the detection signal is output, and a reference value indicating a position corresponding to the absolute position sensor that outputs the detection signal. A position calculation unit that calculates the absolute position of the operation target axis in the rotation direction based on
The operation amount calculation unit that calculates the operation amount of the operation target axis based on the information of the target position in the rotation direction of the operation target axis and the absolute position of the operation target axis calculated by the position calculation unit. When,
Based on the operation amount calculated by the operation amount calculation unit, the operation unit that operates the operation target shaft within the rotatable range from the first position to the second position in the rotation direction of the operation target shaft. Prepare ,
The absolute position sensor is
A first electrode formed on one surface of a printed circuit board arranged in the vicinity of the operation target axis and connected to a power supply line via a resistance element, and a first electrode.
A second electrode formed on the other surface of the printed circuit board and having a GND potential,
Includes a short plate that is joined to the outer peripheral surface of the operation target shaft and is configured to short-circuit the first electrode and the second electrode when the operation target shaft is in the third position. ,
The short plate the first electrode and the second electrode and the rotation control device that is configured to output a voltage change that occurs in the first electrode to the position calculating unit as the detection signal when the short-circuited.

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